Dissociable gaseous hydrocarbon anode for igneous electrolytic furnaces, particularly for aluminum-making



Aug. 18, 1959 FERRAND 2,900,319

DISSOCIABLE GASEOUS HYDROCARBON ANODE FOR IGNEOUS ELECTROLYTIC FURNACES,PARTICULARLY FOR ALUMlNUM MAKING Filed Oct. 14, 1957 5 Sheets-Sheet 1-2,900,319 RBON ANODE FOR IGNEOUS ELECTROLYTIC FURNACES, PARTICULARLY FORALUMINUMMAKING L. FERRAND Aug. 18, 1959 DISSOCIABLE GASEOUS HYDROCA 3Sheets-Sheet 2 .Filed Oct. 14, 1957 Aug. 18, 1959 FERRAND 2,900,319

DISSQCIABLE GASEOUS HYDROCARBON ANODE FOR IGNEOUS ELECTROLYTIC FURNACES,PARTICULARLY FOR ALUMINUM-MAKING Filed Oct. 14, 1957 5 Sheets-Sheet 3Unite States DISSOCIABLE GASEOUS HYDROCARBON ANODE FOR IGNEOUSELECTROLYTIC FURNACES, PARTICULARLY FOR ALUMINUM-MAKING Louis Ferrand,Paris, France Application October 14, 1957, Serial No. 690,060

Claims priority, application France October 19, 1956 7 Claims. (Cl.204-284) This invention relates to novel arrangements applied to theanodes of the dissociable gaseous hydrocarbon type utilized for thecontinuous and automatic operation of igneous electrolytic furnaces,notably for manufacturing aluminum.

The US. Patent No. 2,593,741, granted on April 22, 1952 to the applicantrecites with reference to its second exemplary embodiment illustrated inFigs. 3 and 4 of the drawings the use of relatively narrow passagesformed through the anode mass for introducing in the molten electrolyte,in the specific case of aluminum manufacture, an intimate mixture ofpulverulent alumina with a dissociable gaseous hydrocarbon, the outputof this mixture fed through the anode being such that the atomic carbonresulting from its dissociation at the electrolyzing temperature iseffective in the anodic oxidation reactions as a substitute for thecarbon of the supporting mass.

This dissociation, in the specific case of methane, takes placeaccording to the following reaction:

wherein the variation in free energy is positive for temperatures closeto the room temperature, zero at 850 C. and negative thereabove, so thatthe dissociation of one molecule of methane at the temperature requiredfor electrolyzing aluminum will absorb about 22,000 calories.

Extensive research work demonstrated that it was preferable to preventthe methane gas from entering-even through very narrow passages-theinterpolar gap and being dissociated therein, but that on the contrarythis dissociation should preferably be allowed to take place within thevery heart of this anode mass, that is in its lower strata.

These works also made it possible to ascertain the mechanism of thisdissociation and the critical distance to be maintained between themethane delivery point and the anode surface in view of enabling thechemically pure carbon issuing from this dissociation to agglomerate onthe anode surface in the form of a perfectly adherent spongy layerconstantly renewed as it undergoes the anodic oxidation.

Moreover, these experiments proved that specific arrangements must beprovided to prevent the hydrogen resulting from this dissociation fromcontacting the electrolytic bath, for the water vapor resulting from itsanodic oxidation might produce at least partially the decomposition ofone of the four component elements of the bath, that is, the aluminumfluoride, as the decomposition reactions concerning the other sodium andcalcium fluoride are thermodynamically not feasible.

In view of the foregoing it is the object of this invention to providean anode of the type adapted to be fed with dissociable gaseoushydrocarbon type for effecting an igneous electrolysis, which ischaracterized in that the carbon resulting from the dissociation of thegaseous hydrocarbon will agglomerate at the end of the anode surface inthe form of a perfectly adherent spongy layer, and that the hydrogenreleased by this dissociation is prevented from leaking in the bath bythe provision of adequate suction means.

To this end, the anode comprises a stationary metal casing closed at itsupper end by a fluid-tight partition and containing the anode mass;through this wall and with the interposition of a plurality of glandpackings extend one or more steel studs having an axial passage formedtherein, adapted to be supplied with a gaseous hydrocarbon underpressure, these studs also acting both as means for supporting the anodemass and as lead-in terminals.

Moreover, the following dispositions are preferably resorted to:

Each stud is surrounded by a cylindrical metal sheath in which the levelof the anode mass'is higher than at the outside.

These sheaths are slightly longer than said studs and shorter than theheight of the metal casing.

The lower end portion of this anode mass is substantially concave andhas a flat peripheral or marginal portion.

The volume defined by the stationary outer metal casing, by thehorizontal sealing partition overlying it, by the outer surface of saidmetal sheaths and by the upper level of the anode mass is vacuumizedthrough a duct connected to a suction device.

According to the present invention, the anode mass consists essentiallyof either a mixture of sintered rare earths having a sufficientelectrical conductivity, such as tantalum oxide, or more simply amixture of carbon paste the grain size of which--in the burned state-iscalculated to impart a sufficient porosity to the supporting mass,either of these mixtures being enclosed according to known means in astationary outer casing of square, rectangular or cylindrical shape.

If the selected supporting mass is a carbon paste, the latter will haveits height limited to that currently provided for pre-burned anodes andbe burned beforehand all along its height in the electrolytic furnaceproper so that it will have an adequate porosity before the gaseousmethane is fed thereto.

The above-described means will indisputably lead to a novel industrialresult in that they make it possible to carry out the anodic reductionwith the assistance of chemically pure carbon from the dissociation of agaseous hydrocarbon without allowing the latter or the hydrogenresulting from its dissociation to penetrate the electrolyte and causethe decomposition, even to a limited extent, of one or several componentelements of this electrolyte.

In order to afford a clearer understanding of this invention and of themanner in which the same may be carried out in the practice, referencewill now be made to the accompanying drawings forming part of thisspecification and illustrating diagrammatically by way of example a fewtypical embodiments of the invention. In the drawings:

Figure 1 is a vertical section showing structural details of an anodeconstructed in accordance with the teachings of this invention.

Figure 2 is a plane View of the same'anode.

Figure 3 is a vertical fragmentary section showing on a larger scale thelower portion of theanode.

Figure 4 is an elevational View of an electrolytic furnace equipped withanodes according to a modified embodiment of the invention.

Figure 5 is a fragmentary vertical section showingthe furnace on alarger scale, and

Figure 6 is a view partly in horizontal section,. partly in plane view,showing the furnace equipped with the anodes of this invention, thesection being taken upon the line VIVI ofFig. S.

According to a first embodiment of the invention which is illustrated inFigs. 1, 2 and 3 of the drawings, the anode mass or each of the anodemasses ifa plurality of them are provided in the furnace has anelongated shape and the top of the outer metal casing 1 is closed in afluidport the anode mass according to the known technique in view ofpermitting the vertical sliding displacement of this mass in the outermetal casing 1; of course, these studs 5 also act as current lead-interminals and in the specific case of this invention they are adapted tosupply the furnace with gaseous methane under a pressure P higher thanthe atmospheric pressure. Moreover, each stud 5 is surrounded by acylindrical sheath 8 secured to the horizontal lid 6 and somewhat longerthan the studs themselves so as to create around each stud a neutralzone free of any 'gas circulation.

The lower face of the supporting mass 2 proper is slightly concave asshown at 2:: except for a Hat outer peripheral or marginal portion 2baffording a sufiicient contact area between this mass and the conductingbottom of the furnace to permit the passage of current and, by the Jouleeffect, cause firstly the burning of the raw mass until it has asufiicient porosity, and then the smelting of the bath. The upper levelof this supporting mass is much higher at 9 than inside the sheaths soas to create a sufficient adherence between the studs 5 and the paste12,

zmolten electrolyte 4 in which the supporting mass is immersed.

To this end, the free space surrounding the sheaths 8 is partlyvacuumized by means of a pipe line 10 connected to a suitable suctiondevice (not shown) operating at a pressure P lower than the atmosphericpressure.- The lower ends of these sheaths 8 (which, as already stated,are somewhat longer than the studs 5) form together a surface designatedby the dotted line 8a in Figs. 1 and 3, substantially at an equal andvery short distance from the lower concave surface 2a of the supportingmass, whereby the gaseous methane issuing from the lower ends of thestuds 5 must necessarily flow along substantially downward paths in thesheaths 8 as its temperature rises until its dissociation begins, thatis, when the gaseous stream enters the layer 3.

Finally, the outer metal casing 1 has fitted around its lower portion afrusto-conical hood 11 adapted, according to the known fashion, tocollect the electrolysis gases formed above the carbonaceous layer 3 onaccount of the anodic oxidation at a pressure approximating theatmospheric pressure P,,.

The ratios of the pressures P and P to the pressure l will be determinedpresently in connection with the description of the mechanism by whichthe carbon layer 3 is formed and the residual gases resulting from thedissociation of the gaseous methane are discharged.

Now this descriptionwill bear:

Firstly, on the means to be used during the period in which the atomiccarbon layer 3 is pre-formed when starting the electrolytic furnace;

Secondly, the means to be used when, as this atomic carbon layer hasattained a sufficient thickness, the gasfed anode according to thisinvention begins to operate normally.

(A) Pre-formation period Fig. 3 illustrates in section and on a largerscale the lower end of one of the hollow steel studs 5 surrounded by itscircular sheath 8 and formed with at least one orifice 5a through whichthe gaseous methane under the pressure P is fed to the furnace. Thedistance X measured between the lower end 5b of these studs 5 and thelower face 2a of the supporting mass is determined by constructionaccording to the teachings of experience, so that, with dueconsideration for the porosity of the supporting mass utilized and forthe velocity at which the gaseous methane is fed (this velocity beingobviously.

subordinate to the pressure P the time of travel of the methane fed tothe furnace, as measured from the outlet end of the hollow stud 5 to thelower face 5a of the supporting mass, enables the methane to attain thetemperature of the electrolytic bath proper, that is, about 950 C., atwhich the dissociation according to the reaction CH =C+2H, in the caseof gaseous methane, is

practically instantaneous.-

During the pre-formation period the methane output fed through the anodemust be greater than the output required under normal operatingconditions in order to permit only the anodic oxidation reactionsaccording to the strength of the electrolyser, so that the weight ofcarbon black deriving from the methane gas dissociation be substantiallygreater than that oxidised as a consequence of the electrolysis ofalumina, and that a re- .serve of carbon black represented by the layer2a, 3a

-carbonaceous layer 3 may take place beforehand either in a specialelectrolytic furnace fed with alternating current, so that thispre-formation will be faster and more economical, or in a neutralatmosphere maintained in a furnace equipped with heating resistorsproviding a temperature of about 950 C.

(B) Normal operation period When the carbon layer 3 has attained asufficient thickness the free spaces surrounding the sheaths 8 arevacuumized through the pipe 10 to a negative pressure P of such valuethat the hydrogen released by the dissociation of the methane cannotpenetrate in the bath but is caused to travel by suction around thesheaths 8 as indicated by the arrows in Fig. 3.

Each bubble of hydrogen is released during the dissociation at thepressure P at which the gaseous methane was introduced in the supportingmass minus the loss of pressure J1 resulting from the travel of thisbubble from the outlet end of stud 5 to the point where its builds up,but only within the layer 3 provided that the distance X was correctlycalculated.

around the sheaths 8 above the level 9:: of the supporting mass, and 11the loss of pressure resulting from the travel of the residual gasesthrough the supporting mass 2 above the sheaths 8, it is evident thateach hydrogen bubble thus formed will not penetrate the liquid bath butwill be sucked up around the sheaths 8 if the pressure P +h is slightlylower than the surface pressure existing at the lower face 3a contactingthe liquid bath, that is, the atmospheric pressure plus the pressurecorresponding to the height or head of the liquid bath in which thesupporting mass is immersed, this last-mentioned pressure being about1.06 kilograms in the specific case of the manufacture of aluminumelectrolysis.

On the other hand, the residual pressure P h is obviously equal to thepressure P +h at the time the hydrogen bubble is released.

These explanations are summarized by the two relations:

wherein the Relation 2 expresses the limit value which must not beoverstepped by P in order to prevent the residual gases from beingexpelled with the electrolysis gases.

On the other hand, it is evident that when this pressure P becomes lowerthan this limit, it may happen that one fraction of the electrolysisgases themselves be sucked up around the sheaths 8 in admixture with theresidual gases, this condition being preferable to the reverse situationset forth in the preceding paragraph.

As the critical distance X (Fig. 3) was calculated on a reduced-scalemodel to the value necessary and suificient to cause the dissociation ofthe methane to occur in the preformed carbon layer 3, it will berelatively easy to determine the pressures P and P2 to be used byresorting to known means of which only the principle will be remindedhereafter.

In the first place it will be necessary to measure separately the volumeof input gaseous methane and the volume of output residual gas; if acomplete dissociation is obtained the second volume will be twice theformer, in the specific case of methane, the input volume beingsubordinate to the desired intensity of the electrolyser. Theelectrolytic gas output must also be calculated.

In the second place, by assaying the residual gases de livered throughthe suction pipe and the electrolytic gas output issuing from the hood11, it will be possible to check the correct adjustment of the pressuresP and P according as whether hydrogen is present in the electrolyticgases (which is detrimental), or electrolytic gases (CO-I-CO is presentin the residual gases (which is preferable).

Finally, according to these output measurements and gas assays, acomparison between the weight of carbon supplied with the input methaneand the weight of carbon issuing with the electrolytic gases willindicate Whether the input of methane is correct or not. If the weightof carbon is greater at the outlet than at the inlet, it means that thisinput is insufiicient and that the anodic oxidation takes place partlyat the expenses of the carbon reserve of the layer 3. If, on thecontrary, the weight of input carbon is greater than that of outputcarbon, the logical inference is that the input of methane is too high,and in this case the only drawback will be an increase in the thicknessof the reserve layer 3 and consequently a reduction in the inter-polegap, an inconvenience that can be easily avoided by a proper voltageadjustment.

According to another form of embodiment illustrated in Figs. 4, 5 and 6of the drawings wherein the general constructional arrangements providedin Patent No. 2,- 825,690 are described, the supporting mass consists ofthree concentric annular layers A, B and C of approximately equalsection, enclosed between a stationary cylindrical metal casing 13 andan axial funnel 14 of stainless steel, these layers being separated fromone another by cylindrical metal partitions 15 also concentric to thefunnel 14, each layer being divided into approximately equal sectors byradial partitions 16 connecting these different concentric cylindricalcasings with one another.

Each concentric annular layer, if considered as being developed to afiat surface to facilitate the understanding, is arranged like each ofthe rectangular anodic masses of elongated form which are illustrated inFig. 1 according to the first form of embodiment of the invention. Thelayers are definitely independent of one another and each of them isprovided, as in the first form of embodiment, with separate means forpermitting its vertical dis- 6 placement, other adjustment means forsetting the current strengthto values 1,, I 1 adequately determined foreach layer, separate pipe lines 17a, 17b, for supplying each layer withgaseous methane, and adjustment means (not shown) for regulating thedelivery of meth ane to values D D D proportional to the aforesaidcurrent strengths 1,, I I;,, other separate pipe lines being providedfor discharging the residual gases resulting from the dissociation ofthe methane, as shown at 18a, 18b, 180. The only member common to thethree concentric layers is the axial funnel 114 through which theelectrolytic gases are expelled, thisfunnel being also. provided underits lid with a heat recuperator comprising vertical tubes 19 and havingsuspended therefrom a highly-polished parabolic stainless steel mirror20 according to the means described in the aforesaid patent.

On the other hand, in this form of embodiment the reservoirs for thesupply of fluidified alumina which were provided in the aforesaid patentare dispensed with, this alumina being introduced directly through thefree surface of the bath according to known means. Similarly, the holesformed in the intermediate third of the axial funnel are also omitted,since it is not necessary to renew the carbon-paste supporting massburned at the start.

In addition, each of the concentric layers A, B, C described hereaboveis provided, according to its. thickness, with one or two rows of hollowfixation bolts. 21 secured for each of these layers on either side of aseparate ring member 28, these bolts being surrounded by sheaths 22having their ends positioned within a short distance of the innersurface of each layer, this surface having in the radial direction theslightly concave shape described hereabove and intended to improve theadherence and the formation of the pre-formed carbon black layer.

Of course, the outer metal casing 13, the axial funnel 14 and theintermediate cylindrical partitions 15 are interconnected in afluid-tight manner at their upper portions by means of a horizontalpartition 23 on which are secured the cylindrical sheaths 22 throughwhich the aforesaid hollow bolts 21 extend with the interposition ofgland packings 24, each of the closed annular gaps A, B, C thus formedbeing provided with separate suction ducts 18a, 1812, and 180.

In each annular space A, B or C the level of the carbonaceous mass 25ais much lower than the level 25 of the same mass but inside the sheath22 in order to permit the venting of the residual gases from thedissociation of the gaseous methane under the negative pres sure P whilea pressure P higher than the atmospheric pressure obtains in thesesheaths 22 so that the gaseous methane can flow through the carbon blacklayer 24 where its dissociation takes place.

According to the means described hereinabove a com parison between theoutputs, complemented bya quantitative analysis between the gaseousmethane delivered by the studs of each layer and the residual gasesrestituted by each of these layers may be effected for each of theconcentric layers A, B and C, in order to permit the proper adjustment,for each layer, of the respective values of the aforesaid pressures Pand'P However, no specific comparison can be made in view of checkingwhether the weight of carbon introduced with the methane is actuallyequal to the weight of carbon delivered with the electrolytic gases foreach layer A, B, C under permanent operating conditions. As the whole ofthe electrolytic gases resulting from the anodic oxidation of the carbonblack surface layer is vented through the axial funnel 14, only a globalcomparison will permit to ascertain Whether neither a fresh supply noran extraction from the carbon black layer 26 taken as a whole is made.

To simplify the procedure, if the upper portions of the intermediatecylindrical partitions 15 and the axial fun nel 14 are perforated thevacuum created in this axial funnel by its separate duct 27, providedthat it is properly adjusted, may be sufficient to simultaneously directthe residual gases through the carbonaceous mass surround ing thesheaths 22 and discharging these gases in admixture with theelectrolysis gases, so that in this specific case the separate suctionducts 18a, 18b and 180 of the concentric layers A, B and C may bedispensed with.

Thus, a mixture of hydrogen, carbon monoxide and carbon dioxide would becollected as if the dissociation had not taken place and the anodicoxidation had therefore been effected at the expenses of the gaseousmethane itself according to either of the following two reactions, inthe case contemplated herein:

It is known that these reactions occur secondarily in the cracking ofmethane (which is effected at 850 C.) so that the residual gases thuscollected, in admixture with the electrolysis gases, may be treated asthey actually are in the cracking of methane in view of extracting purehydrogen intended for the synthesis of ammonia.

This final remark lays stress on the interest of the present inventionconsisting essentially in reducing the alumina by means of chemicallypure carbon, this method necessarily producing pure metal, this carbonissuing from the dissociation of gaseous methane or any other adequategaseous hydrocarbon, being however much more economical than any otherpre-burned or self-burning oxidizable anodes manufactured from oil cokeas is customary in this kind of electrolysis. Moreover, a gaseousmixture suitable for producing pure hydrogen for the manufacture ofammonia would be available by way of by-product.

What I claim is:

1. An anode for an electrolytic furnace, of the type adapted to be fedwith dissociable gaseous hydrocarbon and immersed in the furnaceelectrolyte, which comprises a stationary metal casing consisting of avertical cylinder open at the bottom, a fluid-tight horizontal plateclosing the top of said metal casing, a porous anodic mass enclosed insaid casing, metal studs disposed vertically in said casing andextending through said horizontal plate in a fluid-tight manner, saidmetal studs being formed with an axial passage adapted to supply at thelower end of said studs a gaseous hydrocarbon under pressure, said studsalso serving as means for supporting the anodic mass and as currentlead-in terminals, a cylindrical metal sheath secured to said horizontalplate and surrounding each of said studs, the level of the anodic massin each sheath being considerably higher than that of the anodic massincluded outside said sheaths, the length of said sheaths being slightlygreater than that of said studs,

said porous anodic mass surrounding and extending below the lower openends of said studs and sheaths.

2. An anode for an electrolytic furnace, of the type adapted to be fedwith dissociable gaseous hydrocarbon and immersed in the furnaceelectrolyte, which comprises 3. An anode for an electrolytic furnace, ofthe type adapted to be fed with dissociable gaseous hydrocarbon andimmersed in thefurnace electrolyte, which comprises a stationary metalcasing consisting of a vertical cylinder open at the bottom, afluid-tight horizontal plate closing the top of said metal casing,aporous anodic mass enclosed in said casing and having its lower faceformed with a concave central portion and a fiat marginal portion, metalstuds disposed vertically in said casing and extending through saidhorizontal plate, said metal studs being formed with an axial passageadapted to supply at the lower end of said studs a gaseous hydrocarbonunder pressure, said studs also serving as means for supporting theanodic mass as current lead-in terminals, gland packings surroundingsaid studs in said fluid-tight horizontal plate, a cylindrical metalsheath secured to said horizontal plate and surrounding each of saidstuds, the level of the anodic mass in each sheath being considerablyhigher than that of the anodic mass included outside said sheaths, thelength of said sheaths being slightly greater than that of said studs,said porous anodic mass surrounding and extending below the lower openends of the studs and sheaths, the geometrical locus of the lower end ofeach sheath being a concave surface equally spaced from the concavecentral portion of the lower anodic surface.

4. An anode for an electrolytic furnace, of the type adapted to be fedwith dissociable gaseous hydrocarbon and immersed in the furnaceelectrolyte, which comprises a stationary metal casing consisting of avertical cylinder open at the bottom, a fluid-tight horizontal plateclosing the top of said metal casing, a porous anodic mass enclosed insaid casing and having its lower face formed with a concave centralportion and a flat marginal portion, metal studs disposed vertically insaid casing and extending through said horizontal plate, said metalstuds being formed with an axial passage adapted to supply at the lowerend of said studs a gaseous hydrocarbon under pressure, said studs alsoserving as means for supporting the anodic mass as current lead-interminals, gland packings surrounding said studs in said fluid-tighthorizontal plate, a cylindrical metal sheath secured to said horizontalplate and surrounding each of said studs, the level of the anodic massin each sheath being considerably higher than that of the anodic massincluded outside said sheaths, the length of said sheaths being slightlygreater than that of said studs, said porous anodic mass surrounding andextending below the lower open ends of the studs and sheaths, a suctiondevice and a duct connecting said a stationary metal casing consistingof a vertical cylinder open at the bottom, a fluid-tight horizontalplate closing the top of said metal casing, a porous anodic massenclosed in said casing and having its lower face formed with a concavecentral portion and a flat marginal por tion, metal studs disposedvertically in said casing and extending through said horizontal plate,said metal studs being formed with an axial passage adapted to supply atthe lower end of said studs a gaseous hydrocarbon under pressure, saidstuds also serving as means for supporting the anodic mass and ascurrent lead-in terminals, gland packings surrounding said studs in saidfluid-tight horizontal plate, a cylindrical metal sheath secured to saidhorizontal plate and surrounding each of said studs, the level of theanodic mass in each sheath being considerably higher than that of theanodic mass included outside said sheaths, the length of said sheathsbeing slightly greater than that of said studs, said porous anodic masssurrounding and extending below the lower open ends of said studs andsheaths.

suction device to the space defined by said stationary metal casing,said fluid-tight horizontal plate and the outer surface of said metalsheaths.

5. An anode for an electrolytic furnace, of the type adapted to be fedwith dissociable gaseous hydrocarbon and immersed in the furnaceelectrolyte, which comprises a stationary metal casing consisting of avertical cylinder open at the bottom, a fluid-tight horizontal plateclosing the top of said metal casing, a porous anodic mass enclosed insaid casing, coaxial cylindrical partitions in said casing a pluralityof concentric annular layers in said anodic mass, radial partitionsconnecting said coaxial cylindrical partitions, each of said layershaving a lower surface of toroidal shape which is slightly concave inthe radial direction, the lower level of each layer increasing from theoutside to the inside, an axial funnel extending through said centrallayer, metal studs disposed vertical ly in each of said layers andextending through said hori zontal plate, said metal studs being formedwith an axial passage adapted to supply at the lower end of said studs agaseous hydrocarbon under pressure, external supports of said studsacting as current lead-in terminals, gland V packings surrounding saidstuds in said fluid-tight horizontal plate, a cylindrical metal sheathsecured to said horizontal plate and surrounding each of said studs, thelevel of the anodic mass in each sheath being considerably higher thanthat of the anodic mass included outside said sheaths, the length ofsaid sheats being slightly greater than that of said studs, and theporous anodic mass in each layer surrounding and extending below thelower open ends of the studs and sheaths.

6. An anode for an electrolytic furnace as set forth in claim 5,comprising a suction device associated with each of said annular layersand a duct connecting each of said sunction devices to the free spacedefined by said fluid-tight horizontal plate, said coaxial cylindricalpartitions, said casing and the upper level of the associated layer,whereby the pressure is so adjusted for each of said suction devicesthat the hydrogen issuing from the dissociation of the methane gas bedrawn around the sheaths and will not penetrate the bath.

7. An anode for an electrolytic furnace as set forth in claim 5,comprising perforations provided in the upper portion of theintermediate cylindrical partitions above said anodic mass, perforationsin said axial funnel above said anodic mass, and a suction deviceconnected to said axial funnel, whereby the pressure is adjusted in saidaxial funnel to cause the hydrogen issuing from the dissociation of themethane gas to be drawn completely by this axial funnel while beingmixed up with the electrolysis gases.

References Cited in the file of this patent UNITED STATES PATENTS

1. AN ANODE FOR AN ELECTROLYTIC FURNACE, OF THE TYPE ADAPTED TO BE FEDWITH DISSOCIABLE GASEOUS HYDROCARBON AND IMMERSED IN THE FURNACEELECTROLYTE, WHICH COMPRISES A STATIONARY METAL CASING CONSISTING OF AVERTICAL CYLINDER OPEN AT THE BOTTOM, A FLUID-TIGHT HORIZONTAL PLATECLOSING THE TOP OF SAID METAL CASING, A POROUS ANODIC MASS ENCLOSED INSAID CASING, METAL STUDS DISPOSED VERTICALLY IN SAID CASING ANDEXTENDING THROUGH SAID HORIZONTAL PLATE IN A FLUID-TIGHT MANNER, SAIDMETAL STUDS BEING FORMED WITH AN AXIAL PASSAGE ADAPTED TO SUPPLY AT THELOWER END OF SAID STUDS A GASEOUS HYDROCARBON UNDER PRESSURE, SAID STUDSALSO SERVING AS MEANS FOR SUPPORTING THE ANODIC MASS AND AS CURRENTLEAD-IN-TERMINALS, A CYLINDRICAL METAL SHEATH SECURED TO SAID HORIZONTALPLATE AND SURROUNDING EACH OF SAID STUDS, THE LEVEL OF THE ANODIC MASSIN EACH SHEATH BEING CONSIDERABLY HIGHER THAN THAT OF THE ANODIC MASSINCLUDED OUTSIDE SAID SHEATHS, THE LENGTH OF SAID SHEATHS BEING SLIGHTLYGREATER THAN THAT OF SAID STUDS, SAID POROUS ANODIC MASS SURROUNDING ANDEXTENDING BELOW THE LOWER OPEN ENDS OF SAID STUDS AND SHEATHS.